#include <stdio.h>   
#include <math.h>   
int main()   
{long long s=0;   
 int v[1000001],i,j,n;   
    
     
 freopen("fractii.in","r",stdin);   
 freopen("fractii.out","w",stdout);   
 scanf("%d",&n);   
    
  for(i=1;i<=n;i++)     
     v[i]=i-1;     
      
 for(i=2;i<=n;i++)     
     {for(j=2*i;j<=n;j+=i)     
         v[j]-=v[i];     
     s+=v[i];}     
    
 printf("%lld",2*s+1);   
  return 0;}